The conventional liquid-cooled internal combustion engine relies primarily on axial flow fans to draw cooling aft from outside of the vehicle through the liquid-to-air heat exchanger or radiator for cooling. Various efforts have been made to improve cooling, including increasing the liquid capacity of the radiator, increasing the size or number of fan blades, and changing the pitch of the fan blades.
Cooling system demands vary widely depending on the type of vehicle and its use. Many truck programs have an issue where a maximum amount of cooling is required by virtue of maximum radiator airflow especially during hot weather and towing heavy loads, up hills, with or without large trailers.
In addition to variations based on vehicle type and use, the HVAC demands also play a role in cooling system efficiency. The aft conditioning system must also maximize heat transfer out of the refrigerant loop via the condenser. These conditions are the most demanding at high ambient temperatures and at low speeds. Since most cooling packages have cooling fans that pull from behind the radiator, it is imperative that the condenser (which is positioned in front of the radiator) is sealed to the radiator around its perimeter.
During the development of truck programs (particularly in large displacement engines and/or powertrains with turbochargers and charge air coolers that promote a large towing capacity), powertrain cooling finds a need to delete side seals mentioned above during high powertrain demand. Conversely, the air conditioning system requires that these side seals stay in place for low speeds and idle conditions in hot weather.
As in so many areas of vehicle technology there is always room for improvement related to the cooling arrangements for liquid-cooled internal combustion engines.